A383061 Positive integers that contain an odd digit d immediately preceded by a digit >= d.

11, 21, 31, 33, 41, 43, 51, 53, 55, 61, 63, 65, 71, 73, 75, 77, 81, 83, 85, 87, 91, 93, 95, 97, 99, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 121, 131, 133, 141, 143, 151, 153, 155, 161, 163, 165, 171, 173, 175, 177, 181, 183, 185, 187, 191, 193, 195, 197, 199

Offset: 1

Author

Paolo Xausa, Apr 18 2025

Keywords

• nonn
• base
• easy

Comments

Conjecture: these are the numbers missing from A383059.

Links

• Paolo Xausa, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A383059, A383062 (complement).

Cf. A347298, A382464, A382623, A382937, A383245, A383247, A383249, A383500.

Programs

Mathematica

A383061Q[k_] := MemberQ[Partition[IntegerDigits[k], 2, 1], {i_, j_?OddQ} /; i >= j];
Select[Range[200], A383061Q]

Python

def ok(n):
    s = str(n)
    return any(s[i] <= s[i-1] for i in range(1, len(s)) if s[i] in "13579")
print([k for k in range(200) if ok(k)]) # Michael S. Branicky, Apr 19 2025